1. Field
One or more embodiments of the present invention relate to an image generation system, method and medium, and more particularly, to an image generation system, method and medium which can acquire a plurality of images with different luminance in a single photographing operation and generate a high dynamic range image from the acquired images.
2. Description of the Related Art
When image photographing apparatuses, such as digital cameras and camcorders, photograph a subject against background light, they generate images having different exposures in order to enhance image sensitivity. Then, the image photographing apparatuses synthesize the generated images and provide the synthesized image to a user.
Specifically, when an identical subject is photographed using different exposure times, the shorter the exposure time, the higher the contrast of the image and thus the clearer the edges of the image. In addition, the longer the exposure time, the clearer the color of the image. Therefore, if an image acquired using a long exposure time and an image acquired using a short exposure time are synthesized, a high dynamic range image can be obtained.
Referring to FIG. 1, a conventional image photographing apparatus generates a first image 11 acquired using a short exposure time, and a second image 12 acquired using a longer exposure time relative to the first image 11, synthesizes the first and second images 11 and 12, and generates a high dynamic range image 13.
In order to acquire images with different luminance through multiple exposures, a user has to maintain the same posture for a predetermined period of time, which is usually inconvenient to the user. Furthermore, if the user's hands tremble or shake while maintaining the same posture, image blurring occurs. Alternatively, even if the user can maintain the same posture for the predetermined period of time, if the position of a subject is changed while the user is taking photographs of the subject, the images acquired through the photographing operation are not identical. Consequently, it is difficult to generate a normal image.
A method of changing structures, such as modifying an array of color filters or varying sensitivity of the color filters, has been used so as to eliminate the inconvenience of users having to the maintain the same posture for a predetermined period of time. However, the method requires additional processing, such as demosaicing of the color filters and white balancing.
U.S. Patent Publication No. 2006-0066750 discloses an image sensor which can generate a wide dynamic range image by exposing odd-numbered columns of pixels in a pixel array for a short period of time, exposing even-numbered columns of pixels in the pixel array for a longer period of time than the odd-numbered columns of pixels, combining the odd-numbered columns of pixels and the even-numbered columns of pixels into respective pairs, and outputting the respective pairs of the odd-numbered columns of pixels and the even-numbered columns of pixels. However, the conventional art fails to suggest a method of eliminating the inconvenience to users of having to maintain the same posture for a long exposure time, or a technique for preventing image blurring due to the trembling hands of the users.
In this regard, a method of generating a high dynamic range image using images acquired in a single short exposure is required.